Bare electronic chips typically need to be packaged in a package that provides an electric circuit to each electrical connection of the chip and to an external connector such as a pin or a ball. Typical is a pin-grid array package having relatively large pins on one side for external connections, and pads on an opposite side for connections to a ball-grid-array set of connections to the electronic chip (such as a processor or memory chip). Also typical is a ball-grid array package having relatively large balls with relatively large spacings on one side of the package for external connections, and small closely spaced pads on the same side for connections to a ball-grid-array set of connections to the electronic chip (such as a processor or memory chip).
Such a package typically has a non-conductive substrate (such as a plastic film or layer) with conductive traces (wires) on or in a surface of the substrate. Some packages include multiple chips, such as a logic or processor chip, as well as a memory chip, such as a FLASH-type reprogrammable non-volatile memory. Balls and/or pins are attached to the outside of the package, and one or more electronic chips are attached, for example, by also using ball-grid-array connection methods and/or flying-wire methods. Optionally, a cover or encapsulant is used to enclose the chip or chips.
One conventional way to make such a package is to start with a sheet or strip of non-conductive material such as Mylar film, then deposit a film of metal such as copper, then pattern and etch the metal to leave traces. The chips are then connected to the traces on the Mylar film and encapsulated to form the package. With one chip at one end of the film, and another chip at an opposite end, the traces to connect the signals at the far ends of the chips can be longer than desired.
What is needed is a simple, inexpensive, reliable method and apparatus to fabricate packages for electronic chips, so that the package is compact and the traces are relatively short.